In a heterogeneous radio communication system several types of wireless access network nodes are serving mobile stations. A radio access network of the radio communication system may provide for example so-called macro cells, so-called micro cells, so-called pico cells, and/or so-called femto cells in order to offer wireless coverage with a variety in size of wireless coverage zones for different environments, ranging from an open outdoor environment to office buildings, homes, and underground areas.
A macro cell is a radio cell in the radio communication system that provides broadest radio coverage by a highest output power and that may be located for example in rural areas or along highways. The macro cell is comparable to a base station of a 2G or 3G radio communication system (2G/3G=Second/Third Generation) such as GSM/GPRS (GSM=Global System for Mobile Communication, GPRS=General Packet Radio Service) or UMTS (UMTS=Universal Mobile Telecommunication Systems). Antennas for macro cells are mounted on ground-based masts, rooftops and other existing structures, at a height that provides a clear view over surrounding buildings and terrain.
A micro cell with a smaller coverage area than the macro cell may be deployed in a densely populated urban area. Pico cells are deployed for areas even smaller than those for micro cells. An example of usage for a pico cell would be a large office, a mall, or train station. Currently the smallest area of coverage can be implemented by a femto-cell, which may be deployed in homes or small offices.
In a downlink direction of radio frequency signals, which are transmitted from the wireless access network nodes to a mobile station, which is attached to and served by a smaller cell (micro cell, pico cell, femto cell), an interference situation within the smaller cell is usually dominated by the macro cell that covers the smaller cell or that intersects the smaller cell.